fs/omfs/file.c

   1 /*
   2  * OMFS (as used by RIO Karma) file operations.
   3  * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
   4  * Released under GPL v2.
   5  */
   6
   7 #include <linux/module.h>
   8 #include <linux/fs.h>
   9 #include <linux/buffer_head.h>
  10 #include <linux/mpage.h>
  11 #include "omfs.h"
  12
  13 static u32 omfs_max_extents(struct omfs_sb_info *sbi, int offset)
  14 {
  15         return (sbi->s_sys_blocksize - offset -
  16                 sizeof(struct omfs_extent)) /
  17                 sizeof(struct omfs_extent_entry) + 1;
  18 }
  19
  20 void omfs_make_empty_table(struct buffer_head *bh, int offset)
  21 {
  22         struct omfs_extent *oe = (struct omfs_extent *) &bh->b_data[offset];
  23
  24         oe->e_next = ~cpu_to_be64(0ULL);
  25         oe->e_extent_count = cpu_to_be32(1),
  26         oe->e_fill = cpu_to_be32(0x22),
  27         oe->e_entry.e_cluster = ~cpu_to_be64(0ULL);
  28         oe->e_entry.e_blocks = ~cpu_to_be64(0ULL);
  29 }
  30
  31 int omfs_shrink_inode(struct inode *inode)
  32 {
  33         struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
  34         struct omfs_extent *oe;
  35         struct omfs_extent_entry *entry;
  36         struct buffer_head *bh;
  37         u64 next, last;
  38         u32 extent_count;
  39         u32 max_extents;
  40         int ret;
  41
  42         /* traverse extent table, freeing each entry that is greater
  43          * than inode->i_size;
  44          */
  45         next = inode->i_ino;
  46
  47         /* only support truncate -> 0 for now */
  48         ret = -EIO;
  49         if (inode->i_size != 0)
  50                 goto out;
  51
  52         bh = omfs_bread(inode->i_sb, next);
  53         if (!bh)
  54                 goto out;
  55
  56         oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
  57         max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);
  58
  59         for (;;) {
  60
  61                 if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
  62                         goto out_brelse;
  63
  64                 extent_count = be32_to_cpu(oe->e_extent_count);
  65
  66                 if (extent_count > max_extents)
  67                         goto out_brelse;
  68
  69                 last = next;
  70                 next = be64_to_cpu(oe->e_next);
  71                 entry = &oe->e_entry;
  72
  73                 /* ignore last entry as it is the terminator */
  74                 for (; extent_count > 1; extent_count--) {
  75                         u64 start, count;
  76                         start = be64_to_cpu(entry->e_cluster);
  77                         count = be64_to_cpu(entry->e_blocks);
  78
  79                         omfs_clear_range(inode->i_sb, start, (int) count);
  80                         entry++;
  81                 }
  82                 omfs_make_empty_table(bh, (char *) oe - bh->b_data);
  83                 mark_buffer_dirty(bh);
  84                 brelse(bh);
  85
  86                 if (last != inode->i_ino)
  87                         omfs_clear_range(inode->i_sb, last, sbi->s_mirrors);
  88
  89                 if (next == ~0)
  90                         break;
  91
  92                 bh = omfs_bread(inode->i_sb, next);
  93                 if (!bh)
  94                         goto out;
  95                 oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
  96                 max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
  97         }
  98         ret = 0;
  99 out:
 100         return ret;
 101 out_brelse:
 102         brelse(bh);
 103         return ret;
 104 }
 105
 106 static void omfs_truncate(struct inode *inode)
 107 {
 108         omfs_shrink_inode(inode);
 109         mark_inode_dirty(inode);
 110 }
 111
 112 /*
 113  * Add new blocks to the current extent, or create new entries/continuations
 114  * as necessary.
 115  */
 116 static int omfs_grow_extent(struct inode *inode, struct omfs_extent *oe,
 117                         u64 *ret_block)
 118 {
 119         struct omfs_extent_entry *terminator;
 120         struct omfs_extent_entry *entry = &oe->e_entry;
 121         struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
 122         u32 extent_count = be32_to_cpu(oe->e_extent_count);
 123         u64 new_block = 0;
 124         u32 max_count;
 125         int new_count;
 126         int ret = 0;
 127
 128         /* reached the end of the extent table with no blocks mapped.
 129          * there are three possibilities for adding: grow last extent,
 130          * add a new extent to the current extent table, and add a
 131          * continuation inode.  in last two cases need an allocator for
 132          * sbi->s_cluster_size
 133          */
 134
 135         /* TODO: handle holes */
 136
 137         /* should always have a terminator */
 138         if (extent_count < 1)
 139                 return -EIO;
 140
 141         /* trivially grow current extent, if next block is not taken */
 142         terminator = entry + extent_count - 1;
 143         if (extent_count > 1) {
 144                 entry = terminator-1;
 145                 new_block = be64_to_cpu(entry->e_cluster) +
 146                         be64_to_cpu(entry->e_blocks);
 147
 148                 if (omfs_allocate_block(inode->i_sb, new_block)) {
 149                         be64_add_cpu(&entry->e_blocks, 1);
 150                         terminator->e_blocks = ~(cpu_to_be64(
 151                                 be64_to_cpu(~terminator->e_blocks) + 1));
 152                         goto out;
 153                 }
 154         }
 155         max_count = omfs_max_extents(sbi, OMFS_EXTENT_START);
 156
 157         /* TODO: add a continuation block here */
 158         if (be32_to_cpu(oe->e_extent_count) > max_count-1)
 159                 return -EIO;
 160
 161         /* try to allocate a new cluster */
 162         ret = omfs_allocate_range(inode->i_sb, 1, sbi->s_clustersize,
 163                 &new_block, &new_count);
 164         if (ret)
 165                 goto out_fail;
 166
 167         /* copy terminator down an entry */
 168         entry = terminator;
 169         terminator++;
 170         memcpy(terminator, entry, sizeof(struct omfs_extent_entry));
 171
 172         entry->e_cluster = cpu_to_be64(new_block);
 173         entry->e_blocks = cpu_to_be64((u64) new_count);
 174
 175         terminator->e_blocks = ~(cpu_to_be64(
 176                 be64_to_cpu(~terminator->e_blocks) + (u64) new_count));
 177
 178         /* write in new entry */
 179         be32_add_cpu(&oe->e_extent_count, 1);
 180
 181 out:
 182         *ret_block = new_block;
 183 out_fail:
 184         return ret;
 185 }
 186
 187 /*
 188  * Scans across the directory table for a given file block number.
 189  * If block not found, return 0.
 190  */
 191 static sector_t find_block(struct inode *inode, struct omfs_extent_entry *ent,
 192                         sector_t block, int count, int *left)
 193 {
 194         /* count > 1 because of terminator */
 195         sector_t searched = 0;
 196         for (; count > 1; count--) {
 197                 int numblocks = clus_to_blk(OMFS_SB(inode->i_sb),
 198                         be64_to_cpu(ent->e_blocks));
 199
 200                 if (block >= searched  &&
 201                     block < searched + numblocks) {
 202                         /*
 203                          * found it at cluster + (block - searched)
 204                          * numblocks - (block - searched) is remainder
 205                          */
 206                         *left = numblocks - (block - searched);
 207                         return clus_to_blk(OMFS_SB(inode->i_sb),
 208                                 be64_to_cpu(ent->e_cluster)) +
 209                                 block - searched;
 210                 }
 211                 searched += numblocks;
 212                 ent++;
 213         }
 214         return 0;
 215 }
 216
 217 static int omfs_get_block(struct inode *inode, sector_t block,
 218                           struct buffer_head *bh_result, int create)
 219 {
 220         struct buffer_head *bh;
 221         sector_t next, offset;
 222         int ret;
 223         u64 uninitialized_var(new_block);
 224         u32 max_extents;
 225         int extent_count;
 226         struct omfs_extent *oe;
 227         struct omfs_extent_entry *entry;
 228         struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
 229         int max_blocks = bh_result->b_size >> inode->i_blkbits;
 230         int remain;
 231
 232         ret = -EIO;
 233         bh = omfs_bread(inode->i_sb, inode->i_ino);
 234         if (!bh)
 235                 goto out;
 236
 237         oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
 238         max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);
 239         next = inode->i_ino;
 240
 241         for (;;) {
 242
 243                 if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
 244                         goto out_brelse;
 245
 246                 extent_count = be32_to_cpu(oe->e_extent_count);
 247                 next = be64_to_cpu(oe->e_next);
 248                 entry = &oe->e_entry;
 249
 250                 if (extent_count > max_extents)
 251                         goto out_brelse;
 252
 253                 offset = find_block(inode, entry, block, extent_count, &remain);
 254                 if (offset > 0) {
 255                         ret = 0;
 256                         map_bh(bh_result, inode->i_sb, offset);
 257                         if (remain > max_blocks)
 258                                 remain = max_blocks;
 259                         bh_result->b_size = (remain << inode->i_blkbits);
 260                         goto out_brelse;
 261                 }
 262                 if (next == ~0)
 263                         break;
 264
 265                 brelse(bh);
 266                 bh = omfs_bread(inode->i_sb, next);
 267                 if (!bh)
 268                         goto out;
 269                 oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
 270                 max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
 271         }
 272         if (create) {
 273                 ret = omfs_grow_extent(inode, oe, &new_block);
 274                 if (ret == 0) {
 275                         mark_buffer_dirty(bh);
 276                         mark_inode_dirty(inode);
 277                         map_bh(bh_result, inode->i_sb,
 278                                         clus_to_blk(sbi, new_block));
 279                 }
 280         }
 281 out_brelse:
 282         brelse(bh);
 283 out:
 284         return ret;
 285 }
 286
 287 static int omfs_readpage(struct file *file, struct page *page)
 288 {
 289         return block_read_full_page(page, omfs_get_block);
 290 }
 291
 292 static int omfs_readpages(struct file *file, struct address_space *mapping,
 293                 struct list_head *pages, unsigned nr_pages)
 294 {
 295         return mpage_readpages(mapping, pages, nr_pages, omfs_get_block);
 296 }
 297
 298 static int omfs_writepage(struct page *page, struct writeback_control *wbc)
 299 {
 300         return block_write_full_page(page, omfs_get_block, wbc);
 301 }
 302
 303 static int
 304 omfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 305 {
 306         return mpage_writepages(mapping, wbc, omfs_get_block);
 307 }
 308
 309 static void omfs_write_failed(struct address_space *mapping, loff_t to)
 310 {
 311         struct inode *inode = mapping->host;
 312
 313         if (to > inode->i_size) {
 314                 truncate_pagecache(inode, inode->i_size);
 315                 omfs_truncate(inode);
 316         }
 317 }
 318
 319 static int omfs_write_begin(struct file *file, struct address_space *mapping,
 320                         loff_t pos, unsigned len, unsigned flags,
 321                         struct page **pagep, void **fsdata)
 322 {
 323         int ret;
 324
 325         ret = block_write_begin(mapping, pos, len, flags, pagep,
 326                                 omfs_get_block);
 327         if (unlikely(ret))
 328                 omfs_write_failed(mapping, pos + len);
 329
 330         return ret;
 331 }
 332
 333 static sector_t omfs_bmap(struct address_space *mapping, sector_t block)
 334 {
 335         return generic_block_bmap(mapping, block, omfs_get_block);
 336 }
 337
 338 const struct file_operations omfs_file_operations = {
 339         .llseek = generic_file_llseek,
 340         .read_iter = generic_file_read_iter,
 341         .write_iter = generic_file_write_iter,
 342         .mmap = generic_file_mmap,
 343         .fsync = generic_file_fsync,
 344         .splice_read = generic_file_splice_read,
 345 };
 346
 347 static int omfs_setattr(struct dentry *dentry, struct iattr *attr)
 348 {
 349         struct inode *inode = d_inode(dentry);
 350         int error;
 351
 352         error = setattr_prepare(dentry, attr);
 353         if (error)
 354                 return error;
 355
 356         if ((attr->ia_valid & ATTR_SIZE) &&
 357             attr->ia_size != i_size_read(inode)) {
 358                 error = inode_newsize_ok(inode, attr->ia_size);
 359                 if (error)
 360                         return error;
 361                 truncate_setsize(inode, attr->ia_size);
 362                 omfs_truncate(inode);
 363         }
 364
 365         setattr_copy(inode, attr);
 366         mark_inode_dirty(inode);
 367         return 0;
 368 }
 369
 370 const struct inode_operations omfs_file_inops = {
 371         .setattr = omfs_setattr,
 372 };
 373
 374 const struct address_space_operations omfs_aops = {
 375         .readpage = omfs_readpage,
 376         .readpages = omfs_readpages,
 377         .writepage = omfs_writepage,
 378         .writepages = omfs_writepages,
 379         .write_begin = omfs_write_begin,
 380         .write_end = generic_write_end,
 381         .bmap = omfs_bmap,
 382 };
 383